An exemplary case of a typical Heterogeneous Network (HetNet) comprises a plurality of suitable powered macrocells for providing wide coverage range in sufficiently large areas. However, deployment of such macrocells may suffer quick capacity degradation as the number of user equipment operating in the macrocells coverage areas increases. Therefore, operators are also, now reinforcing the macrocells deployment along with at least one Wi-Fi placed at multiple strategic locations within one or more macro coverage areas. This kind of reinforced cellular network is generally termed as Heterogeneous network (herein after referred to as HetNet). Further a typical HetNet, reinforced with small cells placed at multiple strategic locations, not only provides increased mobile data capacity but also provides better mobile coverage, thereby enhancing the overall user's mobile broadband experience. The strategic location may include, but not limited to, areas having high density of users (such as shopping malls, airports, railway/bus stations and colleges), dead-spot areas, areas with low macro signal strength (such as indoor establishments) and peripheral locations of a macro coverage area.
In recent years, wireless technologies based on IEEE 802.11 standards, specifically the Wi-Fi technology, have undergone tremendous growth and commercialization. Presently, nearly all available user equipments (UE) with cellular capability support are now been integrated with the Wi-Fi in order to connect with all the available Wi-Fi networks operating in various unlicensed frequency bands including, but not limiting to, 2.4 GHz and 5 GHz. Such advancements in the Wi-Fi technologies therefore, have been playing a motivating role for cellular operators in usage of ubiquitous and cost-effective Wi-Fi technology while pursuing their HetNet strategy. Accordingly, a number of operators are now deploying low powered Wi-Fi cells along with cellular small cells at multiple strategic locations identified for the HetNet.
In an exemplary embodiment, a typical HetNet comprises a macro base station for providing wide area coverage to service users. Within the macro cell coverage, a plurality of low power nodes are being employed in service areas having a higher density of users requiring high data rates, wherein the low power nodes comprise micro cells that are integrated with Wi-Fi radio to provide multi-technology hotspot capacity/coverage goals. Alternatively, the operators could deploy independent and cost-effective Wi-Fi Access points in hotspot areas in order to offload cellular load, thereby sufficing with capacity/coverage requirements of users. Further, in the HetNet, the macro base station coverage may be used for wide area overlay mobility coverage, while the micro base stations along with coverage of the Wi-Fi access points may be used for upgrading the mobile capacity.
Further, the 3rd Generation Partnership Project (3GPP) standard particularly outlines two types of access i.e. trusted and untrusted non-3GPP access, wherein the non-3GPP access includes, but not limited to, the access from Wi-Fi, Worldwide Interoperability for Microwave Access (WiMAX), fixed and Code Division Multiple Access (CDMA) networks, while the trusted non-3GPP Wi-Fi access was first introduced with the long Term Evolution (LTE) standard in 3GPP Release 8 (2008). The trusted access is usually anticipated to be an operator-built Wi-Fi access with encryption in the Wi-Fi radio access network (RAN) and a secure authentication method. Particularly, in the trusted access, the user equipment is connected through a trusted wireless access gateway (TWAG) in the Wi-Fi core, wherein the TWAG is in turn connected directly with a packet gateway in the evolved packet core (EPC) through a secure tunnel (such as GPRS (General Packet Radio Service) Tunneling Protocol Computing (GTP), Mobile Internet protocol (MIP) or Proxy Mobile IP (PMIP)). On the other hand, the untrusted model was first introduced in the Wi-Fi specification in 3GPP Release 6 (2005). In the untrusted access, the operator has no control over the Wi-Fi access points such as public hotspots, subscribers' home Wi-Fi and Corporate Wi-Fi. Therefore, such untrusted Wi-Fi access points do not provide sufficient security mechanisms such as authentication and radio link encryption. Furthermore, the untrusted model requires no changes to the Wi-Fi RAN (Radio Access Network) but has an impact on the device side which requires an Internet Protocol Security (IPSec) client in the device, wherein the device is connected directly to the evolved packet data gateway (ePDG) in the Evolved Packet Core (EPC) through a secure IPSec tunnel. The Evolved Packet Data Gateway (ePDG) is connected to the Packet Gateway (P-GW) where each user session is transported through a secure tunnel (GTP or PMIP).
Considering the flaws and limitations in the non-trusted Wi-Fi access, the telecom service operators are considering a green field deployment of trusted Voice Over Wi-Fi (VoWiFi) solution to enable any Subscriber Identification Module (SIM) subscriber to make/receive an emergency call (video or voice) from any un-trusted/un-managed WiFi access such as the Voice over Long-Term Evolution (VoLTE) emergency calls. Therefore, the operators are proposing to offer these VoWiFi emergency services for SIM based subscribers locally over any un-trusted/un-managed Wi-Fi environment. Further, there have been spurt of emergency incidents across the globe and threatening environment and therefore, there has been a demand from the users and the investigators for an emergency alert mechanism on the devices. While conventional techniques may be available on many of the user equipments on other wireless channels there are no mechanism to identify an emergency call on the WiFi channel and route the same to the nearest local authorities/emergency centers to respond and help the victims in emergency situations. The location information is critical for two main reasons in emergency services. The initial purpose of the location information is to enable the IP Multimedia Subsystem (IMS) network to determine which public-safety answering point (PSAP) serves the area where the UE is currently located, so that the IMS network can route the emergency call to the correct PSAP. The second purpose is for the PSAP to get more accurate or updated location information for the terminal/device during or after the emergency session required by local authorities to ascertain the facts of the emergency incidence.
Accordingly, in order to overcome the aforementioned problems inherent in the existing solutions for establishing an emergency call over a wireless LAN network, there exists a need of an efficient mechanism to facilitate VoWiFi emergency services for the SIM based subscribers of the user equipments (registered VoWiFi among various clusters of WiFi) locally over any un-trusted/un-managed Wi-Fi network.